ritiro del Mais Starlink

["AlessandroGimona"<agimona@libero.it>]

Cari tutti,

in un editoriale che  scritto qualche mese fa ("Chi semina vento.."  che 
trovate andando alla home page di Peacelink http://www.peacelink.it/)  
Peacelink contestava le accuse di facile allarmismo e metteva in luce 
uno dei rischi della modificazione genetica delle colture difficili da 
controllare: la contaminazione della catena alimentare umana.

Il recente caso del mais Stalink, ritirato dal mercato perche' non 
autorizzato per il consumo umano, supporta le nostre tesi.


Includo due articoli del New York times che servono ad approfondire la 
questione.

Spero interessi,
Saluti

Alessandro Gimona
agimona@libero.it


CASE ILLUSTRATES RISKS OF ALTERED FOOD
         Oct. 14 2000
         N.Y. Times
         ANDREW POLLACK
         http://www.nytimes.com/2000/10/14/science/14HEAL.html
         The genetically engineered corn that is linked to a widening 
web of food
         recalls has not been approved for human consumption because, 
according to
         this story, it contains a protein that is not normally part of 
the human
         food supply and that shares some characteristics of known food 
allergens.
         But there is no evidence that the corn actually does cause 
allergies, and
         some experts say that consumers need not worry about eating 
products that
         might contain the corn.
         T. P. King, professor emeritus at Rockefeller University in New 
York, who
         was on a scientific advisory panel formed by the Environmental 
Protection
         Agency to evaluate the potential allergenicity of the corn, 
which is known
         as StarLink, was quoted as saying, "I do not believe it's 
likely to cause
         any allergies,"
         For its part, the environmental agency said on Thursday that it 
"believes
         the risks, if any, are extremely low."
         Still, the story says the case illustrates what some critics of
         biotechnology say is a potential risk of genetically engineered 
foods ‹ that
         it is difficult to determine whether such foods will cause 
allergies.
         Jane Rissler, senior staff scientist at the Union of Concerned 
Scientists in
         Washington., was quoted as saying,"We don't know and the E.P.A. 
doesn't know
         and the allergists don't know."
         Indeed, the advisory panel examining StarLink concluded earlier 
this year
         that "there is no
         evidence to indicate" that the protein "is or is not a 
potential food
         allergen."
         The story says that StarLink, made by Aventis SA, is one of 
several
         genetically modified corn strains known as BT corn, so named 
because they
         contain a gene from the Bacillus thuringiensis bacteria that 
causes the corn
         to produce a toxin that kills insects. BT toxins derived 
directly from the
         microbes have been used for decades as pesticidal sprays and 
are a favorite
         of organic farmers because they are natural.
         While there is at least one report of farm workers' developing 
antibodies to
         the toxin, these sprays have generally been given a clean bill 
of health for
         farm workers and consumers. And that is one reason the 
environmental agency
         has been willing to approve several types of crops corn, 
potatoes and cotton
         ‹ with BT genes. But the StarLink BT toxin, known as Cry9C, is 
from a
         different strain of bacteria than the others and has not been 
used in
         sprays.
         In some cases, allergenicity can be tested in advance. Several 
years ago, a
         seed company
         transplanted a gene from the Brazil nut into soybeans in order 
to make a
         more nutritious
         bean. But tests done on the blood of people with known 
allergies to Brazil
         nuts found that
         those people would have also suffered reactions to the 
genetically modified
         soy. That soybean was never marketed.
         But because Cry9C comes from a type of bacteria that has not 
been part of
         the human diet, there are no people with known allergies to the 
bacteria who
         could provide blood for allergy tests. And there are no 
validated animal
         tests that can predict human allergies.
         So scientists try to decide safety based on the physical and 
chemical
         characteristics of the
         protein. Many proteins that cause food allergies are not 
digested readily by
         the acids and
         enzymes in the stomach, are heat stable, have attached 
carbohydrates and are
         present in food in high levels, according to the agency's 
review documents.
         But none of these characteristics are absolute predictors of 
causing
         allergies, and there are proteins with one or more of these 
characteristics
         that are not allergens.
         The Cry9C has two of these characteristics. It does not break 
down quickly
         when exposed to an acid bath simulating stomach conditions and 
also can
         withstand heat treatment at 90
         degrees Celsius for 10 minutes.
         On the other hand, the protein is in low concentrations in the 
corn, and the
         amino acid
         sequence of Cry9C does not resemble the sequence of any other 
known
         allergens. Aventis maintains that there is no evidence that 
carbohydrates
         are attached to the protein, although the federal report says 
there is some
         evidence of this.
         Some experts say that even if Cry9C is a potential allergen, 
people might
         not suffer reactions now because the corn is new to the food 
supply.
         Usually, people must be exposed to an allergen over time to 
become
         sensitized to it.
         Steve L. Taylor, professor of food science and technology at 
the University
         of Nebraska, was quoted as saying in a statement issued by 
Kraft Foods when
         it recalled its taco shells found to contain StarLink that, "In 
my opinion,
         there is virtually no risk associated with the ingestion of 
StarLink corn in
         this situation."
         Dr. King of Rockefeller University also noted said that 
proteins were most
         often allergenic in their natural form. But corn is consumed 
only after
         cooking or food processing, which could destroy or change the 
shape of the
         protein.
         Indeed, none of the tests done so far have actually detected 
the Cry9C
         protein ‹ the potential allergen ‹ in any of the food products 
that have
         been recalled. The tests have detected the Cry9C gene, which is 
made of DNA.
         It is possible that in food processing the DNA survived but the 
protein did
         not, some experts said. However, the protein in this case is 
stable when
         heated, increasing its chances of surviving intact.



         NEW CONCERNS RISE ON KEEPING TRACK OF MODIFIED CORN
         Oct. 14 2000
         N.Y. Times
         KURT EICHENWALD
         http://www.nytimes.com/2000/10/14/science/14FOOD.html
         Efforts to trace shipments of a bioengineered corn unapproved 
for human
         consumption have, according to this story, raised concern among 
food and
         grain industry officials that the corn ‹ which has already been 
discovered
         in two brands of grocery products ‹ may have made its way more 
widely into
         production channels for the nation's food supply.
         The story says that food companies, many of which are now 
testing every
         shipment of corn for signs of the unapproved grain, have 
reacted with dismay
         to growing evidence of contamination, saying that it 
demonstrates a
         breakdown in the procedures intended to keep products grown 
from genetically
         modified seeds separate from conventional grains.
         One food company executive, speaking on condition of anonymity, 
was quoted
         as saying, "This whole system has been self- policing by the 
seed industry.
         And obviously it hasn't worked."
         The story says that the concern about StarLink has strained 
relations
         between the nation's grain companies and the developer of the 
corn, Aventis
         Crop Science, a subsidiary of Aventis S.A. of France. For 
example, according
         to a communication to the organization's members, the National 
Grain and
         Feed Association has demanded that the company reveal the names 
of the more
         than 2,000 farmers growing StarLink crops, information that 
would allow the
         industry to track potentially contaminated shipments more 
quickly.
         But those requests have been refused. The grain association has 
since filed
         a request with the Environmental Protection Agency under the 
Freedom of
         Information Act, seeking the names of those farmers.
         On Sept. 29, shortly after the first detection of contaminated 
taco shells,
         Aventis CropScience said it had reached an agreement with three 
federal
         agencies to work together to buy up all of this year's StarLink 
crop and to
         ensure that it had not entered the food supply.
         Since then, the company has contacted the farmers, urging them 
to store the
         corn until further notice and questioning them about how the 
product had
         been handled.
         What was found, according to industry officials who have been 
briefed on the
         results, is that not all farmers had signed required contracts 
obligating
         them to follow certain procedures intended to keep StarLink out 
of the food
         supply. As a result, the company is now urging elevator 
operators to begin
         testing corn shipments for the presence of the modified grain.
         John Wichtrich, vice president and general manager of Aventis 
CropScience,
         was quoted as writing to elevator operators that, "This is a 
very sensitive
         matter, and everyone's role in preventing StarLink corn from 
entering
         unapproved channels is critical.".
         The story says that Mr. Wichtrich further urged the elevator 
operators "to
         take those measures you believe necessary to insure that the 
corn you
         purchase is suitable for the use you intend."
         Mr. Wichtrich did not respond to a telephone message seeking 
comment.
         Among the measures the company recommends is that elevator 
operators ask
         corn growers about each delivery to determine if it contains 
StarLink, or if
         it was grown less than 660 feet from a crop of the 
bioengineered corn. Corn
         fields grown in that proximity risk contamination by the 
bioengineered crop.
         While Aventis informed farmers that "buffer zones" of that size 
were
         necessary between StarLink and other corn crops, some farmers 
have been
         found not to have strictly adhered to the instruction.
         "The food industry is very concerned that StarLink has 
contaminated a larger
         portion of the grain supply," one government official involved 
in the matter
         said.
         Two grain industry officials said that based on the information 
they had
         received, as much as 100,000 acres of corn may have been grown 
within the
         buffer zones, in addition to the
         315,000 acres for which StarLink seed was sold.
         In the scramble to keep StarLink out of the food supply, a 
cottage industry
         has emerged in the last two weeks for testing kits to determine 
evidence of
         Cry9C protein, which is present in the bioengineered corn. The 
kits, which
         are used to test corn grain but not processed food, are 
manufactured by
         Strategic Diagnostics of Newark, Del.
         The most common kit, known as a strip test, is used by food and 
grain
         companies at the point of delivery, providing information 
within minutes
         whether a corn shipment has been contaminated with StarLink. An 
individual
         strip test is designed to detect the StarLink protein in 
concentrations
         greater than 0.25 percent, although the sensitivity of the test 
can be
         improved by repeating the test or by increasing the number of 
kernels of
         corn sampled ‹ from 125 to as many as 400.
         At a meeting on Tuesday with officials from the Department of 
Agriculture,
         the
         Environmental Protection Agency and the Food and Drug 
Administration, the
         company
         spelled out details of its contacts with 2,070 farmers who have 
grown the
         StarLink crops.
         In the presentation, according to industry executives who have 
been briefed
         on the results, Aventis CropScience said that it had determined 
that 10.7
         million bushels of StarLink had been fed to livestock, while 47 
million
         bushels remained on the farm or unharvested. Slightly less than 
nine million
         bushels has been delivered into commercial channels.
         Altogether, the StarLink grain represents roughly one-half of 1 
percent of
         this year's corn
         harvest, which totaled more than 10 billion bushels.
         In registered letters to growers of StarLink, the company has 
urged them to
         keep the
         bioengineered corn stored on the farm until they receive 
further
         instructions about where it should be delivered. The farmers 
will be paid a
         premium over the market price for the corn in exchange for 
keeping it
         stored.